Any items or enchants that affect mounted speed will no longer affect any character over level 70. This includes the Riding Crop, Mithril Spurs, Riding Glove Enchant, Carrot on a Stick, Skybreaker Whip and all similar effects. Talents or spells that affect mounted speed will continue to do. In part, we thought it had become a hassle for players to have to equip (or macro) riding trinkets. We have new plans for how to improve mounted speed that we will unveil eventually.

There was actually a thread on the WOTLK section of the WoW-EU forums where a blue asked for feedback and ideas on how to change the system so that we would not need trinkets for mounts anymore (taking up bag-space). Several people, myself among them, responded and made suggestions and the entire thread was later brought up in a post on wowinsider.